Ion exchange compositions are well known in the art and include molecular sieves, clays, and even non-porous inorganic oxides. These compositions are synthesized as powders, but owing to various reasons, e.g., back pressure, must be formed into shaped articles such as extrudates, pellets, pills, spheres, etc., in order to be commercially useful. When formed into various shapes, the articles must possess sufficient physical strength to withstand abrasion or attrition and fracture during use, loading and transit.
In forming such shaped articles it is usual to use a binder or matrix material which can provide such strength yet will not interfere with the properties of the ion exchange composition. Commonly used matrix materials or binders include aluminas and clays since these materials can be mixed easily with the ion exchange compositions and can be formed into shaped articles easily by using techniques such as extrusion.
The art also discloses the use of other binders or matrix materials. For example, U.S. Pat. No. 4,013,732 discloses silica as a matrix material in conjunction with ZSM-5 zeolite. Another reference is U.S. Pat. No. 5,182,242 which discloses the use of a low acidity refractory oxide binder and a hydroxy and/or alkoxy-bridged metallopolymer. The low acidity oxide binders include titania, zirconia and silica, while the hydroxy or alkoxy bridged metallo-polymers include zirconium acetate and titanium methoxide. After the article is formed, e.g., extruded, it is calcined at a temperature of about 260.degree. C. to about 815.degree. C. Finally, U.S. Pat. No. 5,053,374 discloses a process for preparing zeolite catalysts bound with low acidity binders such as silica, titania, etc. The process involves preparing a homogeneous mixture of zeolite, water and low acidity binder in colloidal form. The mixture is extruded, dried and calcined to provide the catalyst.
One common feature of the processes described above is that the extrudates or shaped articles are calcined at relatively high temperatures. It would be advantageous to bind these ion exchange compositions without the high temperature firing step, allowing for a lower cost process for making the shaped articles. Applicants have found that the firing step can be eliminated by using as the binder a hydroxy metal oxide, e.g., hydroxy zirconium oxide. Surprisingly, by using a binder precursor, e.g., zirconyl hydroxychloride and heating the article to temperatures of only about 85.degree. C. to about 120.degree. C. one obtains an article which has good strength and high attrition resistance.